1. Field
Embodiments relate to a resist underlayer polymer, a resist underlayer composition including the same, and a method of patterning using the same.
2. Description of the Related Art
Reducing a size of structural shapes in the microelectronics industry and other related industries, including the manufacture of microscopic structures (e.g., micromachines and magneto-resist heads) has recently attracted attention. In particular, in the microelectronics industry, reducing the size of microelectronic devices in order to provide a greater number of circuits in a given chip size is increasingly desirable. Effective lithographic techniques may be used to achieve a reduction in the size of structural shapes.
A typical lithographic process may involve the following processes. First, a resist coated on an underlying material may be subjected to exposure to radiation to form a resist layer. Thereafter, the resist layer may be subjected to development to provide a patterned resist layer and the underlying material exposed in the patterned resist layer may be etched to transfer a pattern into the underlying material. After transferring the pattern, a photosensitive resist may be subjected to exposure to provide a patterned resist layer. Thereafter, an image may be developed by bringing the exposed resist layer into contact with a certain substance (typically, an aqueous alkaline developing solution). Then, the substance present in openings of the patterned resist layer may be etched to transfer the pattern to the underlying material. After completion of the transfer, remaining portions of the resist layer may be removed.
For better resolution in most lithographic processes, an antireflective coating (ARC) may be used to minimize the reflectivity between a resist layer and an underlying material. However, since many portions of the resist layer may also be removed during etching of ARC after patterning, patterning may be further required in the subsequent etching step.
In other words, in some lithographic imaging processes, the resist may not provide resistance to the etching step to an extent that is sufficient to effectively transfer the desired pattern to an underlying material. In the case where an extremely thin resist layer is required, an underlying material to be etched is thick, a large etching depth is needed, or the use of a particular etchant is required depending on the type of underlying material, a resist underlayer may be used.
The resist underlayer may act as an intermediate layer between the resist layer and the underlying material that may be patterned by transfer from the patterned resist. The resist underlayer should be able to receive the pattern from the patterned resist layer and withstand etching required to transfer the pattern to the underlying material. Although many materials for such an underlayer have been suggested, an improved underlayer composition is needed.
Since conventional underlayer materials may be difficult to apply to substrates, the use of chemical and physical vapor deposition, special solvents, and/or high-temperature baking may be required. However, these methods have a high cost. Thus, an underlayer composition that may be applied by spin-coating techniques without high temperature baking may be desirable. An underlayer composition that may be selectively etched using an overlying resist layer as a mask in an easy manner while being resistant to etching necessary to pattern an underlying metal layer using an underlayer as a mask, may be desirable.
An underlayer composition that provides superior storage life-span properties and avoids unwanted interactions (e.g., acid pollution from a hardmask) with an imaging resist layer may be desirable. An underlayer composition that has particular optical properties against imaging irradiation at short wavelengths (e.g., 157 nm, 193 nm, and 248 nm) may be desirable.